Keep only the variables from the input listed in selections

srckeep(df, selections)

Arguments

df

a disk.frame

selections

The list of variables to keep from the input source

Examples

cars.df = as.disk.frame(cars) # when loading cars's chunks into RAM, load only the column speed collect(srckeep(cars.df, "speed"))
#> speed #> 1: 4 #> 2: 4 #> 3: 7 #> 4: 7 #> 5: 8 #> 6: 9 #> 7: 10 #> 8: 10 #> 9: 10 #> 10: 11 #> 11: 11 #> 12: 12 #> 13: 12 #> 14: 12 #> 15: 12 #> 16: 13 #> 17: 13 #> 18: 13 #> 19: 13 #> 20: 14 #> 21: 14 #> 22: 14 #> 23: 14 #> 24: 15 #> 25: 15 #> 26: 15 #> 27: 16 #> 28: 16 #> 29: 17 #> 30: 17 #> 31: 17 #> 32: 18 #> 33: 18 #> 34: 18 #> 35: 18 #> 36: 19 #> 37: 19 #> 38: 19 #> 39: 20 #> 40: 20 #> 41: 20 #> 42: 20 #> 43: 20 #> 44: 22 #> 45: 23 #> 46: 24 #> 47: 24 #> 48: 24 #> 49: 24 #> 50: 25 #> speed
# clean up cars.df delete(cars.df)